Home / Products / Solar and battery transformers / MV skids for solar and BESS, sizes, brands and what is inside
MV skids for solar and BESS, sizes, brands and what is inside
An MV skid is a factory built block that puts the inverters or power conversion system, the medium voltage transformer and the switchgear on one base or in one container. It arrives wired and tested, so the site only connects DC in and medium voltage out. We quote complete skids and the skid transformer alone, delivered.
What is inside an MV skid
Every skid has the same three layers. The low voltage side holds the inverter or the battery power conversion system and a busbar. The middle is an oil immersed step up transformer, usually 0.8 kV or 0.69 kV on the low side. The medium voltage side is a switchgear or ring main unit with a disconnect, plus auxiliary power for fans and controls.
Makers describe the same idea under different names, including inverter skid, PCS skid, power station skid, MV station and turnkey station. They all mean the same package, so one page covers the whole family.
Skid sizes and published ratings
Most utility scale skids sit between 2.8 and 5 MVA, sized so one skid matches a block of inverters and one transformer. The table lists ratings from the maker datasheets we read. Check the current revision before you design to a figure, because makers change them between releases.
| Skid | Rating | Voltage | Container or size | Notes |
|---|---|---|---|---|
| Solis 4200 MV | 2.80 to 3.15 MW or 4.2 MW transformer options | 12.47 to 34.5 kV to 0.8 kV on the smaller option, 34.5 to 0.8 kV on the 4.2 MW option | 20 ft container | Vector groups Dy1, Dy11 and Ygyg. Built around 1500 VDC string inverters of 250 to 350 kW. |
| SMA MVPS 4600 S2 US | 4600 kVA, 4140 kVA at 40 C | Per project | 20 ft high cube, 6058 by 2896 by 2438 mm | Weight listed under 18 tonnes on the SMA datasheet. The rating depends on the inverter fitted. |
| Sungrow MVS4480 US | 4480 kVA at 40 C, 4928 kVA at 30 C | 0.8 kV to 34.5 kV | 20 ft ISO, 6058 by 2896 by 2438 mm, 16,000 kg | Oil immersed, ONAN or KNAN. Impedance about 8 percent at 34.5 kV. Vector groups Dy1, Dy11, YNy0 or custom. |
| FIMER PVS980 CS US | 4.3, 4.6, 4.8 and 5.0 MVA types, up to 5000 kVA | MV output options up to 36 kV | Compact skid | Oil immersed ONAN transformer. Output drops at 50 C, so confirm the site temperature. |
| Power Electronics MV Skid Solar | 4780 to 4860 kVA at 40 C on the current datasheet, 1910 to 4390 kVA on an older one | 6.6 to 36 kV MV, 660 or 690 V LV | Skid mounted | Two datasheet revisions disagree, so confirm the model with the maker. |
Figures come from the maker datasheets listed under Sources. They are published ratings, not a quote, and they can change by revision.
Skid types
Central inverter stations pair one or two large inverters with a transformer and are the usual choice on utility scale solar. String inverter stations, such as the Solis 4200 MV, collect many 250 to 350 kW inverters on a low voltage busbar feeding one transformer. Battery storage skids use a power conversion system in place of the PV inverter and often add a ring main unit and auxiliary transformer.
The transformer inside is a step up unit and loads like a solar transformer, with frequent cycling and harmonics from the inverters. Our guide on transformers for solar and storage covers the specification points.
Buying the skid or buying the transformer separately
A complete skid is one warranty and one delivery, and the maker has already matched the inverter to the transformer impedance. Buying the transformer and switchgear separately lets you pick the transformer maker and often a closer match to your interconnection voltage, but you carry the integration and the commissioning risk.
If the inverter maker allows a third party transformer, send us the inverter model and we quote a pad mounted or skid transformer to its specification. If the maker requires its own skid, we quote that instead.
Price and lead time
We found no public price for these skids. The makers quote per project, and any price you see on a reseller page is unreliable without the rating, voltage and delivery terms. Lead times are also project quotes and depend on the maker, the transformer and the season. We state the lead time and the country of manufacture on every quote.
What to send for a quote
- Skid rating in kVA or MVA and the inverter or PCS model
- Medium voltage and low voltage, for example 34.5 kV to 0.8 kV
- Vector group and impedance the maker or utility requires
- Site altitude and the highest ambient temperature
- Solar or battery storage, and whether DC coupled
- Whether you want the whole skid or only the transformer
- Delivery ZIP code and the date you need it on site
Common questions
What is an MV skid
An MV skid is a factory built block that combines the inverter or power conversion system, a medium voltage transformer and the switchgear on one base or in one container. It ships wired and tested.
What sizes do MV skids come in
The skids we read range from about 2.8 MW up to 5000 kVA. A 20 foot container version such as the Sungrow MVS4480 US is rated at 4480 kVA at 40 C.
What medium voltage do MV skids use
Most US units step 0.8 kV or 0.69 kV up to a collector voltage, with 34.5 kV the figure that appears on the Solis, Sungrow and Power Electronics datasheets. Other voltages are offered, up to 36 kV on the Power Electronics skid.
Can I buy only the transformer from a skid
Often yes, if the inverter maker accepts a third party unit built to its specification. Send us the inverter model and the required vector group and impedance and we quote the transformer.
How much does an MV skid cost
We found no public price. Skids are quoted per project, so ask for the rating, voltage and delivery terms in writing.
Related pages
Sources
- Solis, Solis 4200 MV skid solution (US)
- SMA, MV Power Station US datasheet
- Sungrow, MVS4480 US datasheet
- FIMER, PVS980 CS up to 5000 kVA US datasheet
- Power Electronics, MV Skid Solar datasheet
Market figures are public asking prices and published industry figures, dated where the source gives a date. They are not our prices. A quote from us is a delivered price for a specific unit.